nodoze Jumping in on this discussion as I'm facing the same challenge. I'm in the process of purchasing a car that has Android Auto. Can I confirm that with your setup, the KSPIV (or similar) device connects to the car's OEM Android Auto system via USB cable (or possibly bluetooth/wifi as well?), and then your Graphene phone connected to the KSPIV and you were still able to make / receive phone calls to the car's OEM hands-free system?
My original plan was to build an oDroid device for this purpose, but it seems the KSPIV would take the manual steps out of this and give me a turnkey solution (win!). However, I'm at a loss as to how the bluetooth phone calls would still work. In my understanding, this could only work if the KSPIV somehow 'forwards' the bluetooth call from the Graphene, through to the car's OEM hands-free. Is that how it's handled?
During the the research phase of my original plan, I took a stock Android phone to the car dealer and connected it to the Android Auto of the car I'm buying. My hope was that I could also then connect my Graphene to the car via bluetooth and have the latter take over the speakers when a call became active, but this didn't work. It was EITHER the Stock Android working on Android Auto, OR it was the Graphene connected for hands-free. I couldn't have both connected simultaneously. Attempts to disable the bluetooth connection on the stock Android were thwarted by Android Auto's ability to overrule the user and just re-enable bluetooth and connect (dammit).
If the device you're using has a workaround for this, it would make me a very happy person. I'm very thankful for any insight you can provide.